The present invention relates generally to electronic circuit modules and, more particularly, to a gasket for use with a hollow core, air-cooled electronic circuit module.
The recent development and ncreased utilization of very large scale integration (VLSI) and very high speed integrated circuit (VHSIC) packages have necessitated intensive investigation into methods for drawing off the heat generated by such circuits. At present, widely used methods include solid core and hollow core modules. A solid core module comprises two printed wiring boards each having surface mount components on one side and each bonded to a thermally-conductive frame material to form a sandwich assembly. Using this type of module, the heat generated into the printed wiring boards by the circuit packages is drawn off by thermal conduction.
In a hollow core module, the printed wiring circuit boards are bonded to a frame such that there is a narrow passage within the frame for the flow of cooling air. The frame may include metal fins within the passage to increase the heat transfer area. Using tnis form of module, the heat generated into the printed wiring boards by the circuit packages is drawn off by convection. Although the hollow core arrangement necessitates the more complex chassis configuration, i.e., ports and manifolds for the controlled flow of cooling air through the chassis and modules, it provides a significant improvement in cooling capacity over its solid core counterpart. As an example, for a solid core module having a thermal capacity in the order of 20 to 40 watts, an equivalently-sized hollow core module will be able to dissipate heat in the order of 70 to 100 watts.
The present invention is directed for use with a hollow core module. It is recognized that providing a proper seal between the hollow core within the frame and the corresponding air port in the chassis maximizes the cooling effect of the air flow therethrough by preventing the leakage of the air from its intended path. However, the required positioning of such a seal, relative to the direction of motion of the module during its insertion into and extraction from the chassis, poses a high risk of damage to the seal.
.In the prior art, the seals have comprised flat gaskets cemented to the sidewalls of the chassis. This arrangement has made repair of a damaged seal very difficult. Such a repair necessitates taking apart the chassis, and special tooling is required to provide a controlled glue line and for centering the gasket around the air slot. Such extensive repair can rarely be effected at the field level; thus, damage to a gasket often disables an entire electronics system while the chassis is returned to depot for repair.